RE: DA 50 problem
Adjust low needle (the one closest to the engen) in or lean it till the engen will not transition to high speed, then richen it till the engin will trensition good.
Then adjust the hight speed needle for max rpm, then back it off lor richen it till you loose about 200 rpm.
After that you can check the low end again.
Good luck.
I am watching you
Larry S